Quick Launch

I had an internet explorer icon on the quick launch bar; it disappeared. What happened?

I booted my machine. The internet explorer icon was on the quick launch bar. I opened two browser sessions. I was reading information from these browser sessions. The computer went to sleep. Right away, I pressed on the power button to awake the computer. I looked at the quick launch bar, and the internet explorer icon was missing.

What happened? Why did the internet explorer icon disappear? I wasn't doing anything that I haven't done a thousand times.

Well, in your occasion, I'm not really sure but there are 2-3 ways it can disappear:

1. Remove it by accident (that's certainly not the case)
2. Some applications with compatibillity issues may re-arrange/remove desktop and/or start menu/quick launch bar shortcuts.
3. There was something wrong with this particular browser session so your computer went to sleep and some settings regarding Internet Explorer changed.

Well, I may be wrong but I have had experienced a similar situation before.